CA2092757A1

CA2092757A1 - Alkenylaminoalkane-1,1-diphosphonic acid derivatives and copolymers thereof with unsaturated carboxylic acids

Info

Publication number: CA2092757A1
Application number: CA002092757A
Authority: CA
Inventors: Matthias Krull; Christoph Naumann; Herrmann Hoffmann
Original assignee: Hoechst AG
Current assignee: Hoechst AG
Priority date: 1992-03-28
Filing date: 1993-03-26
Publication date: 1993-09-29
Also published as: EP0563729A3; US5302677A; JPH0641162A; EP0563729A2; NO931135D0; NO931135L

Abstract

Abstract of the Disclosure:

Alkenylaminoalkane-1,1-diphosphonic acid derivatives and copolymers thereof with unsaturated carboxylic acids The invention relates to alkenylaminoalkane-1,1-diphos-phonic acid derivatives of the formula I

(I) in which R1 to R5, a, b, and Z have the meaning given in the description and to processes for their preparation.
The invention furthermore relates to copolymers compris-ing 0.1-50 mol%, preferably 1-15 mol%, of at least one alkenylaminoalkane-l,1-diphosphonate unit of the formula I
and 99.9-50 mol%, preferably 99-85 mol%, of at least one carboxylic acid unit of the formula II
R6R7C = CR8Y (II) in which R6, R7, R8 and Y have the meaning given in the description and to processes for their preparation. These copolymers are used as scale inhibitors, as alkaline earth metal and heavy metal complexing agents and/or sequestering agents and as builders or co-builders in detergents.

Description

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HOECHST AKTIENGESELLSCE~FT HOE 92/F 078 Dr.Kl/As Description Alkenylaminoalkane~ diphosphonic acid derivatives and copolymers thereof with unsaturated carboxylic acids When oil, water and gas are extracted from underground formations, mixing of incompatible aqueou6 media, and changes in temperature and pressure may result in scale formation. Scale formation can lead, inter alia, to blocking of formations, drilling holes, extraction pipes and pipelines and to ~tuck pumps and valves ancl thus cause loss of production and substantial repair costs.
.
To prPvent scale formation, i.2. precipitation of spar ingly soluble alkalina earth metal salt~, on the one hand, high-molecular weight polycarboxylic acids ~prefer-ably against alkaline earth metal sulfate) and, on theother, low-molecular-weight polyelectrolytes, such as aminomethylenPphosphonic acids (preEe~ably against alkaline earth metal carbonate) are added to saline waters in less than stoichiometric amount~ in the range from 1 to 100 ppm. It is believed that this so-called threshold effect is caused by absorption of the poly-electrolyte on the crystalline surfaces, which disturbs or prevents further crystal growth.

Owing to their good calcium and heavy metal binding power~ aminomethylenephosphonic acids (e.g. Deque~t, ; Monsanto) and other low-molecular-weight polyelec-trolytes, such as, for example, EDTA and triphosphates, also have wide practical application in ~leach washing.
The heavy metals present reduce the shelf life of deter-gent formulation~ and damage the fibers during bleaching.
Likewise, high~molecular-weight polycarboxylic acids are of gr~at importance a~ co-builders in pho~phate-free and phosphate-reduced detergents (Ragnetti; ~enside, .

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2~2Y~7 Surfactants, Detergents 1989,26,30). It is as~umed that they transport water-soluble-metal ions, in particular calcium ions, from the aqueous detergent liquor into the water-soluble zeolites.

Copolymers of alkenylaminomethylenephosphonic acids with unsaturated carboxylic acids which are suitable as complexing agent~, in particular :in detergents, as builders, peroxide stabilizers and as granulating aids for bleaching activator~ and as scals inhibitors having anti-corrosive action in crude oil production are dis-closed in US-A-5,126,418.
.
JP-A-54/135,724 describes a process or the preparation of aminomethylenephosphonic ester~ and antacid hydroly~is thereof to give the free phosphonic acids, for example ~ynthesis of tetraethyl N-diallylaminomethylened:iphos-phonate and the corresponding acid.

JP-A-50/72,987 de~cribes homo- and copolymeri~ation of ~ diallylaminomethylenephosphonic acid with ethylenically `~ unsaturated monomers to give high-molecular-weight (co) polymers. The polymerization of diallylammonium salts produces barely branched polymers containing piperidinium groups tLancaster et al.; Polym. Lett. 1976, 14,549).

Surprisingly, ik has now been found that alkenylamino-alkane-1,1-diphosphonates can be copolymerized with unsaturated carboxylic acids and the copolymers obtained combine the known propertiss of the different monomers in a single compound~

~he present invention relates to alkenylaminoalkane~
diphosphonates of the formula , 2 ~ 3 ( R S ) b ¦ ¦ ¦ o R 3 (CH2=CRI-Z)aN-CR _ p in which is hydrogen or methyl, R2 is hydrogen or C1-C10-alkyl, R3 is Cl-C4-alkyl or phenyl R4 is hydrogen or a cation, preferably sodium, potas-sium or ammonium, R5 is C1-C22-alkyl, C3-C22-alkenyl, preferably propenyl, ; : Z is C~-C3-alkyl and a i~ 1 or 2, b i~ 0 or 1, a + b i9 2.

:10 The alkenylaminoalkane-l,1-diphosphonates according to the inve~tion of the ~orInula I are advantageously ob-tained hy mixing a diester of phosphorous acid, an alkyl orthoformate and an alkenylamine with the addition of a : catalyst, ~uch as boron trifluoride etherate, if desired : 15 in a solvent; and reaction at temperatures in the range from:50 to 150C while distilling off the alcohol formed, followed by alkaline hydrolysis.
~, :Usually, 0.5 to 2.0 mol, preferably 1.0 to 1.3 mol, of alkyl orthoformate and~1.5 to 3.0 mol, preferably 2.0 to 2.5 mol of:the diester of phoephorous ~cid are reacted per mole of the amine in question.

Example~ of suitable diesters of phosphorous acid are dialkyl esters with the Cl-C5-alkyl, such as dimethyl e~ter, diethyl ester, diphenyl ester or alXylaryl ester, 25 : such as benzyl esters.

Preference should be given to amines whose boil.ing point above the boiling point of the resulting alcohol, for 27~
~ 4 --example 3-methylamino-1-propene; 3-ethylamino-1-propene;
3-butylamino-1-propene;3-heptylamino-1-propene;3-amino-1-butene; 4-amino-1-butene; 4-ethylamino-l butene; 3-amino~2-methyl-l-propene; 3-methylamino-2-methyl-l-propene; diallylamine; dimethallylamine; 3-amino-1-pentene; 4-amino-1-pentene; 5-amino-1-pentene. Dial-lylamine is particularly preferred.

Suitable alkyl orthoformates are C1-C4-alkyl esters, in particular ethyl orthoformate.

Suitable solvents should have a boiling point above the boiling point of the resulting alcohol, toluene~ xylene, dichlorobenzene, dimeth~l formamide, dimethyl sulfoxide or nitro~enzene being preferably used.

The alkenylaminoalkanediphosphonic esters formed in the reaction described above are preferably hydrolyzed by addition of bases, such as ~odium hydroxide solution, potassium hydroxide solution or ammonia water to give the compounds according to the invention of the formula I.
Compared with hydrolysis using acid, such as hydrochloric acid, this alkaline hydrolysis has the advantage that formation of the toxic ethyl chloride does not take place. The salts of the compounds of the formula I Eormed during alkaline hydrolysis are obtained in high purity and yield and can be used directly for the copolymerization according to the invention. The addition of, preferably, equimolar amounts of acid/ such as hydrochloric acid, converts the ~alts of the compounds of the formula I into the corresponding acids.

The invention furthermore relates to copolymers contain-ing 0.1 to 50 Mol%, preferably 1 to 15 mol~, of at least one ~; alkenylaminoalkane~ diphosphonate unit of the formula I, in which :
, , , ~, 2~9~
s R3 is additionally hydrogen or a cation, such as sodium, potassium or ammonium, and 99.9 to 50 mol%, preferably 99 to 85 mol%, of at least one carboxylic acid unit of the formula R~R7C=CRaY (II~
in which R6 and R7, independently of one another, are hydrogen, phenyl or a group of the formula COOM, R8 is hydrogen, methyl, phenyl or a group of the formula -CH2-COOM, Y is a group of the formula -COOM- or R7 and R8 together are a C4-alkylene radical, R7 and Y together are a group of the formula -C~O)-O-C(O)-or R8 and Y together are a group of the formula -CH2-C(O)-O-C(O) and in which M is hydrogen, Cl-C6-alkyl or a cation, preferably sodium, potassium or ammoniuml with the proviso that the monomers o the formula II carry one or two carboxylic acid units ;~ 20 of ths formula -C(O)-O- and aontain 0 to 10 mol% of further ethylenically unsaturated mono-mers.

Representatives of suitable monomers of the formula I are diallylaminomethane~ diphosphonic acid, diethyl disodium diallylaminomethane-l,1-diphosphonate, diethyl dipotas~ium diallylaminomethane-1~1-diphosphonate, N-methylallylaminomethane-1,1-diphosphonic acid, disodium N-methylallylaminomethane-1,1-diphosphon~te.
, ~
Representatives of suitable monomers of the formula II
are acrylic acid, methacrylic acid, maleic acid, maleic ` anhydride, itaconic acid and cinnamic acid and lower alkyl esters thereof, such as methyl acrylate and methyl methacrylate.
~, Apart from these monomers, further ethylenically unsat-urated monomers, such as vinyl ~ulfonic acid, vinyl ;~

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phosphonic acid, vinylpyrrolidone! N-vinylacetamide, acrylamide and N- and N,N-substitution products thereoft such as N-methylacrylamide or Z-acrylamido-2-methyl-propanesulfonic acid, and also (meth)allyl compounds, S such as, for example, (meth)allylamine, diallylamine and substitution products thereof, such as methyldiallyl~
amine, octyldiallylamine, diallyldimethylammonium chloride, allylamino-bis(methylenephosphonic acid), allylaminobenzylidenephosphonic acid and diallylamino-methylene phosphonic acid can al~o be added to thepolymerization system. The preferred amount of these comonomers is between 0.001 and 10 mol~.

The copolymers according to the invention are prepared by ;~ initially introducing compounds of the formuIa I as pure substan~es or contaminated with neutxalization salts, such as sodium chloride or sodium sul~ate, in water or in water-miscible organic solvent~t preferably at 20 to 100C, particularly preferably at 40 to 80CI and com-pounds of the formula II and, if desired, further ethyl-enically unsaturated monomers and a radical chain initi-ator, for example ammonium peroxodisulfate, hydrogen peroxide or else tert.butyl hydroperoxide, are added in succession or simultaneously. The total monomer concen-tration is preferably 1 to 60 % by weight, particularly preferably 10 to 60 % by weight, relative to the total weight of the reaction batch. If the compounds of the formula I are water-insoluble alkenylaminoalkanecliphos-phonic acids, they can be made to dissolve by converting them into their aIkaline metal salts or ammonium salts.
Addition of the radical initiator which may be dissolved in a suitable solvent to the reaction vessel can take place simultaneously with or else after addition of the ~; compounds of the formulae I and II.
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A suitable molecular weight for the use according to the invention can be achieved by adding lower alcohols as solvents or else by addition of 0.001 to 30% ~y weight of ~` ~

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a regulator, such as thioglycolic acid, thioethanol, ethanethiol, dodecanethiol, hypophosphorous acid, sodium bi~ulfite to the reaction batch. ~he molecular weight of the copolymers according to the invention is determined by their use, but is in principle not subject to any restriction. The preferred intrinsic visc05ity K (deter-mined by the method of Ubbelohde) of the polymers is, for example for use as scale inhibitor, between 10 and 100, in particular between 10 and 50.

Depending on their intended use, the viscous polymer solutions can be diluted, spray-dried and/or brought to the desired pH by means of bases.

The copolymers according to the inventlon combine the known properties of polyacrylates with those of amino-alkane~ diphosphonic acid derivatives in a singlecompound. In saline forma~ion waters, they lead to effective inhibition of deposit of both alkaline earth metal carbonate and alkaline earth metal sulfates.
- Furthermore, they can be used as alkaline earth metal and i20 heavy metal complexing agents and/or sequestering agents in textile and paper bleaching and the like and, owing to their excellent dispersi~g effect on calcium carbonate, as builder and co-builder in detergents. They can be used in the machine cleaning, bottle cleaning, ste2m produc-tion, cooling water treatment and water treatment ~ectors for preventing scale formation.

~he examples which follow are intended to illustrate the invention without limiting it.
. .
Examples ~`~;30 Percentages are by weight unless stated otherwise. The water used in the examples i5 deionized. The intrinsic viscosity values K were determined by the method of ; ~Ubbelohde at 25C in water and a polymer concentration of :~' .~;~............. .

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5% by weight. Polymerizations were carried out in a 1 1 5-neck flask equipped with flat ground-glass lid~ The flasks are equipped with anchor stirrer, thermometer, reflux condenser, ~as introduction tube and dropping funnel. The solutions initially introduced or polymeriz-ation were flushed with nitrogen.

Example 1 Preparation of diethyl disodium diallylaminomethane~
diphosphonate The preparation of diallylaminomethane-l,1-diphosphonic ester is carried out according to JP-A-53t4~,349.
160 g ~O.42 Mol) of tetraethyl diallylaminomethane-l,l-diphosphonate are taken up in 300 ml of 33% sodium hydroxide solution, and the mixture i8 re1uxed for 4 hours. The resulting colorless precipitate of the di-sodium salt is filtered off with suction, stirred in 50 ml of ethanol and again flltered off with suctionO The colorless product is once again washed with 40 ml of methanol and dried, giving 58 g t38% of theory) of diethyl disodium diallylaminomethane~ diphosphonate as a colorless powder having a melting point of greater than 300~.
: :~
H-NMR ~D20): - 1.2S (t, 6H); 3.38 (t, 1~, JP-C-~ =
24Hz); 3.50 (m, 4H); 3.g3 ~m, 4~; 5.D8-5.40 (m, 4H); 5.68-6.10 (m, 2H)~
31P_NMR (D2) ~ 18.4 PPm, 2JP EI = JP-C-~ - 23.65 Hz ;

Example 2 Preparation of diethyl disodium diallylaminomethane-l,l-diphosphonate ;.~
The procedure of Example 1 is repeated, except that 160 g (0.42 mol) of diethyl diallylaminomethane~ diphos-phonate and 300 ml cf 33% potassium hydroxide solution are used. In this manner, 66 g (38~ of ~heory~ oE diethyl ';

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.

~27~7 g dipotassium diallylaminomethane~ diphosphonate are obtained as a colorless powder having a melting point of greater than 300C. The spectroscopic data are analogous to those of the product prepared according to Example 1.

Example 3 Preparation of diallylaminome~hane~ dipho~phona e 100 g (0.27 mol) of diethyl disodium diallylaminomethane-1,1-diphosphonate are refluxed togeth~r with 200 ml of 37% hydrochloric acid for 4 hours. After removal of the solvent, the product is made to crystallize using a 1:1 mixture of ethanol and petroleum ether. 73 g (99.8~ of theory) of diallylaminomethane~ diphosphonic acid are obtained. Point of decomposition: 140~150C

Example 4 ~:~ 15 Preparation of a copolymer of acrylic acid with 10~ of diethyl disodium diallylaminomethane~ diphosphonate 5 g (0.013 mol) of diethyl disodium diallylaminomethane-diphosphonate are dissolved in a mixture of 100 g of water and 20 g of isopropanol and heated to 75C while introducing a stream of nitrogen. ~t this temperature, a catalyst solution comprising 1.5 g of (~H4)2S20~ in 30 g of water and 45 g of acrylic acid are added dropwise synch-. ronously from two dropping funnels After the exothermic : reaction phase is complete, the reaction mixture is additionally heated at 80C for two hours. ~he colorless ~ 26% polymer solution has an intrinsic viscosity K of 21.
'"
~xample 5 Preparation of a copolymer of acrylic acid with 20% of : diallylaminomethane~ diphosphonate 10.0 g (0.037 mol) of diallylaminomethane-diphosphonic acid are di~solved in a mixture of 80 g of water and 40 g of isopropanol and copolymeri~ed as described in ~xample :
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2~7~7 4, with 40.0 g (0.56 mol) of acrylic acid. The resulting polymer has an intrinsic vi~cosity X of 21.

Example 6 Preparation of a copolymer of acrylic acid with ~0% of diethyl dipotassium diallylaminomethane diphosphonate 10.O g (O.025 mol) of diethyl dipotassium diallylamino-methane~ diphosphonate are copolymerized, as described in Example 5, with 40.0 g ~0.56 mol) of acrylic acid. The resulting polymer has an intrinsic viscosity of 23.

Example 7 Preparation of a copol~mer o acxylic acid with dial-lylaminomethane-l,1-diphosphonic acid USillg ~22 i~S the radical chain initiator `' This copolymer is prepared analogously to Example 4 using 1.5 g of E~20~ as the catalyst~ The resulting polymer has an intrinsic viscosity K of 19.

Example ~
~ Preparation of a terpolymer of acrylic acid with maleic : anhydride and diethyl disodium diallylaminomethane~
diphosphonate 7.5 g (0.02 mol) of diethyl disodium diallylaminomethane-diphosphonate and 20.25 g (0.02 mol) of :maleicanhydride are dissolved in a mixture of 120 g of water ~` and 60 g of isopropanol, and the mixture is heated to 80C while passing a stream of nitrogen through it. At this temperature, a catalyst solution comprising 2.25 g : of (NH4)2S208 in 45 g of water and 47.25 g (0.66 mol) of acrylic acid are added dropwise synchronou~ly from two dropping funnels. After the exothermic reaction phase is complete, stirring at 30~C i8 continued for 4 hours. ~he resulting polymer has an intrinsic viscosity R of 23.
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Example 9 Preparation of a terpolymer of methacrylic acid with 2 acrylamido-2-methylpropanesulfonic acid and diallylamino-methane-1,1-diphosphonic acid 5 g (0.018 mol) of diallylaminomethane-l,1-diphosphonic ` acid are dissolved in a mixture of 60 g of water and 40 g : of isopropanol and the mix~ure is heated to 80C while passing a stream of nitrogen through :it~ At this tempera-ture, a solution of 5 g of 2-acrylamido-2-methylpropane-sulfonic acid and 40 g of methacrylic acid in 20 g of water and a catalyst solu~ion comprising 1.5 g of (NH4~2S2O8 in 30 g of water are added dropwise in parallel : from two dropping funn~ls over a period of 2 hours. After the exotharmic reaction phase is complete, the mixture is additionally heated at 80C for 3 hours. The resulting polymer has a K value of 26.
~.
:~: Example lO
Preparation of a copolymer of aorylic acid with diallyl-: aminomethane-1,1-diphosphonic aaid having a high K value 5 g (0.018 mol) of diallylaminomethane-1,1-diphosphonic acid are dissolved in 100 g of water and copolymerized at : 50C, as descrihed in Example 4, with 45 g (0.63 mol) of acrylic acid. A colorless 34% polymer solution is ob-~:~ tained~ The copolymer has an intrinsic viscosity ~ of 50.

Examples for practical application:

1. Scale inhibition barium sulfate .
~:~ The scale-inhibiting effect is demonstrated by means of a tube plugging test. The principle of this test is to monikor the pressure build-up caused by deposition of solids inside a thermoskated capillary through which a liquid flows. The apparatus selected is a commercial one from S.B. Systems, ~berdeen, of the PMAC type.

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To test for prevention o~ barium sulfate deposits~ the following solutions are mixed:

Solution 1: 74.~2 g/l of NaC1 0.93 g/l of Na2SO4 2.35 g/l Na~CO3 Solution 2: 70.09 g/l of ~aCl 1.21 g/l of BaCl2 1~93 g/1 of CaCl2x2H2O
3.81 g/l M~Cl2x6H2O

The two æolutions are pumped through a ctainless steel capillary of inner diameter of l.l mm with continuous mixing in a mixing section by means of a hose pump. A
sensitive pressure sensor records the increase in pres-sure in the capillary temperature-controll0d at 70DC.

~15 After waiting for a slight increase to about 0~2 bar in ;;~order to effect deposition of a small amount o~ barium sulfate on the steel surface, the inhibitor-free solution 1 is rapidly replaced by an inhibitor-containing solution of the same composition. If the pressure remains con-stant, it is concluded that inhibition of BaSO4 deposition has been successful. If the pressure increases, the amount of inhibitor or, if the c~ncentration i8 the same, the type of inhibitor is insufficient for preventing scale formation. Thus, for rating effectivity, the minimum concentration of inhibitor which only just prevents deposition was taken.

In comparative experiments, the following gradations were observed using this process:

~In the tables below a ~ sign indicates successful -~ ~30 inhibition of scale formation and a --- sign accordingly ~non-inhibition of scale.

2~7~7 Amount of inhibitor ~without solvent) Product30 ppm 20 ppm 17.5 ppm 15 ppm 10 ppm Example 4 ~ + -~- ~~~ ~~~
~xample 5 ~ +~+ +++ ~~~ ~~~
5 Example 6 +++ ~+-~ ++~ ~+~

The compounds according to the invention exhibit an effect against barium sulfate scale deposits even at low concentration.

2. Scale inhibition calcium carbonate ~o test for prevention of calcium carbonate deposits, the following solutions are mixed:

Solution 1: 23.0 g/l of NaCl ~ 2.14 g/l of CaCl2x2H20 : 0.3B g/l of MgCl2x6~2O
0.84 g/l o~ KCl i Solution 2: 23.0 g/l of NaCl : 5.0 g/l of NaHCO3 ~he two solutions are continuously pumped through a ~; mixing cell and then through a stainless steel capillary : 20 of inner diameter 1~1 mm by means of a hose pump. A
sensitive pressure sensor recorded the increase in pres-sure in the capillary temperature-controlled at 80C.

After waiting for an increase to about 0.2 bar in order to effect deposition of a thin calcium carbonate film on ~ 25 the steel sur~ace, the scale inhibitor is continuously .~ metered into the mixing cell via a second pump. I~ the recorded pressure remains constant, it i8 concluded that inhibition of CaCO3 deposition has been succes ful. If the pressure increases, the amount of inhibitor or, if the concentration iB the same, the type of inhibitor is :~ insufficient for preventing scale formation. Thus, for .

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: , ' 2~927~Y~
~ 14 -rating effectivity, the minimum concentration of in-hibitor which only just prevent~ deposition i9 taken.

In comparative experiments, the following gradations are observed using this process:

Amount of inhibitor (without solvent) Product 20 ppm 15 ppm 12 ppm 10 ppm 8 ppm 6 ppm Example 4 ~+ +++ ++~ ~+ - ~~~
Example 5 +++ +++ -~++ +++ +~+ +~+
. ~xample 6 +~+ +++ ~++ +++ +++ ---10 Example 9 +++ ~++ -~

The compounds according to the invention exhibit an effect against calcium caxbonate deposits at lo~w con-centrations.

Remarkably, the higher effectivity, resulting from these tests, of the claimed class of compound, compared with the commercial products, in preventing deposit~ i~ not ~: only obtained: with barium sulfate but also calcium carbonate deposits. This fact is of particular import-ance, since both types of scale can occur jointly, specifically in sea water injection in crude oil ~ deposits, for example in the North Sea.

:~ 3. Calcium-binding power and calcium disper6ion The experimental results u~ing a Ca2+-sensitive electrode (buffer: 0.03 M NH4C1~0,07 N NH3) give, after extrapo-lation of the measuring curves to CpOl~r = 0, the follow-ing binding constant~:
mmol Ca2+ / g of Polymer .~ Example 5 4.3 Example 8 4.5 30 Comparative example 4.0 ~:
,.:.

2~9275~1 The copolymers according to the invention bind CaZ+ better than sodium polyacrylate (MW - 27,000) measured as comparison.

The dispersion of calcium carbonate is determined by the filtration method. CaC03 is precipitated in the presence of the polymer to be tested (test conditions, 4 mmol of ~aClz, 4.4 mmol of Na2CO3, 2 mmol o~ NaOH, 250 ppm of polymer, 40C) and the amount of calcium passing through a filter is determined.

mmol of Ca2+ / g of Polymer Example 5 97%
Example 8 97%
; Comparative example 90%

Al~o with respect to calcium di~persing power, the : 15 polymers according to the invention exhibit better propert.ies than sodium polyacrylate (MW about 27,000) - measured for comparison.
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Claims

1. An alkenylaminoalkane-1,1-diphosphonic acid derivative of the formula I

(I) in which R1 is hydrogen or methyl, R2 is hydrogen or C1-C10-alkyl, R3 is C1-C4-alkyl or phenyl, R4 is hydrogen or a cation, preferably sodium, potassium or ammonium R5 is C1-C22-alkyl, C3-C22-alkenyl, preferably propenyl, z is C1-C3-alkyl and a is 1 or 2, b is 0 or 1, a+b is 2

2. A process for the preparation of an alkenylamino-alkane-1,1-diphosphonic acid derivative as claimed in claim 1, which comprises reacting a mixture of alkenylamine (A), alkyl orthoformate (B) and a diester of phosphorous acid (C) in the presence of a catalyst, if desired in a solvent, at temperatures in the range from 50 to 150°C, component A, B and C
being present in the mixture in the molar ratio of 1:0.5-2.0:1.5-3.0 at the beginning of the reaction and then being subjected to alkaline hydrolysis and, if desired, addition of, preferably, equimolar amounts of acid.

3. A copolymer comprising 0.1-50 mol%, preferably 1-15 mol%, of at least one alkenylaminoalkane-1,1-diphosphonate unit of the formula I

(I) in which R1 is hydrogen or methyl, R2 is hydrogen or C1-C10-alkyl, R3 is C1-C4-alkyl or phenyl and R3 and R4, independently of one another, are hydrogen or a cation, such as sodium, potassium or ammonium, R5 is C1-C22-alkyl, C3-C22-alkenyl, preferably pro-penyl, Z is C1-C3-alkyl and a is 1 or 2, b is 0 or 1, a+b is 2, and 99.9-50 mol%, preferably 99-85 mol% of at least one carboxylic acid unit of the formula II
R6R7C=CR8-Y (II) in which R6 and R7, independently of one another, are hydrogen, phenyl or a group of the formula COOM, R8 is hydrogen, methyl, phenyl or a group of the formula -CH2-COOM, Y is a group of the formula COOM or R7 and R8 together are a C4-alkylene radical, R7 and Y together are a group of the formula -C(O)-O-C(O)- or R8 and Y together are a group of the formula -CH2-C(O)-O-C(O)- and in which M is hydrogen, lower alkyl or a cation, such as sodium, potassium or ammonium, with the proviso that the monomers of the formula II contain one or two carboxylic acid units of the formula -C(O)-O- and contain 0 to 10 mol% of further ethylenically unsaturated monomer units.

4. A copolymer as claimed in claim 3, which contains, as monomer of the formula I, diallylaminomethane-diphosphonic acid and/or diethyl disodium dial-lylaminomethane diphosphonate and/or diethyl di-potassium diallylaminomethane diphosphate incor-porated by polymerization.

5. A copolymer as claimed in claim 3 or 4, which contains, as monomers of the formula II, acrylic acid, methacrylic acid, maleic acid, maleic an-hydride, itaconic acid and/or a lower alkyl ester thereof incorporated by polymerization.

6. A process for the preparation of a copolymer as claimed in one of claims 3 to 5, which comprises polymerizing 0.1 to 50 mol% of a monomer of the formula I with 99.9 to 50 mol% of a monomer of the formula II and, if desired, 0 to 10 mol% of a further ethylenically unsaturated monomer in water and/or in a water-miscible solvent, if desired with the addition of a regulator, in the presence of a radical chain initiator at temperatures of 20 to 100°C, preferably 40 to 80°C.

7. The process as claimed in claim 6, wherein the total monomer concentration is 1 to 60% by weight, prefer-ably 10 to 60% by weight, relative to the total weight of the reaction batch.

8. Use of a copolymer as claimed in claim 3, for pre-venting scale formation, as an alkaline earth metal and heavy metal complexing agent and/or sequestering agent and as builder and co-builder in detergents.